As of now with version 1.8 of Cut the Rope HD on iPad, when the app starts, it says "Welcome back, mike", which is the standard greeting of Game Center.
But there seems to be no where to be found for the leaderboard and achievements? There is a "Crystal" at the lower left of the corner.... but the top players are "Player8945743578" which doesn't mean a whole lot...
Is there some where to be found for the Game Center Leaderboard?
Cut the Rope Experiments HD (v.1.4.1) on the other hand, has that, but is hidden in the "Options" screen... which might be slightly out of place because it really isn't an Option item.